In the 6th century there was a famous whale harassing and attacking ships near Constantinople!
In a Cabinet of Byzantine Curiosities Anthony Kaldellis wrote: “In the days of Justinian I, ships around Constantinople were terrorized on and off for over fifty years by a whale whom locals called Porphyrios, presumably from the dark-wine color of its skin. One day it began to chase and eat some dolphins, but it ran aground in the mud and got stuck. The locals came out with axes and cut it into to pieces. Some of the locals began to eat it on the spot; while others took away their portion to cure (Prokopios, Wars 7.29.16). In Moby Dick, Herman Melville concludes that the whale in this story was a sperm whale (ch. 45).”
In The Wars of Justinian Prokopios described the beast and the issues it caused: “the whale, which the residents of Byzantion (the city of Constantinople) called Porphyrios was caught. This whale had harassed Byzantion and it’s surroundings for over 50 years, but not continuously, for sometimes it would disappear for long periods of time between appearances. It sank many ships and terrified the passengers of many others, forcing them to make great detours from their course. The Emperor Justinian made it a priority to capture the beast, but he could find no way by which to accomplish this.”
Sources:
shadowsofconstantinople.com 